The present invention relates to improvements in self-straining bolts.
Self-straining bolts are known for example from British patent specification No. 1,382,192 which shows a bolt having a central bore which is closed at one end. The bolt is stressed by inserting a rod along the bore into contact with the closed end and applying jacking forces, at the opposite end of the bolt, between the bolt and rod in such a manner as to tension and stretch the shank of the bolt and apply a corresponding compression force to the rod. The clearance created by stretching the bolt is taken up by shims or adjustment of a nut and the jacking forces are then relieved, leaving the bolt under tension. The rod may then be removed.